Highly efficient, polarization insensitive terahertz metamaterial perfect absorber and imaging

In this work we present the design, simulation and characterization of a novel thin, tunable, polarization insensitive metamaterial absorber structures which can behave as a perfect absorber at THz frequencies. Each unit cell of the absorber is made up of two metallic structures separated by a dielectric filler material. The electric response can be tuned by adjusting the geometry of the top metallic electric ring resonator structure, which was designed to contain a square closed ring with four plates arranged 90o from one another inside the ring. These plates form 45o gaps in order to generate an electric response at any incident field polarization. The ground plane provides freedom to place the absorber device on any desired surface since no transmission is allowed beyond the metallic plane. The magnetic response generated by the absorber structure occurs between the two metallic layers. As a result the magnetic response, and thus the absorption, is highly dependent on the dielectric layer thickness.